Multiple chip module cooling system and method of operation thereof

Abstract

Disclosed herein is computer system having a first and second multiple chip modules (MCM) and a cooling module. The cooling module includes a first cooling loop associated with said first MCM and a first evaporator. The cooling module further includes a second cooling loop associated with said second MCM and a second evaporator. Each cooling loop is coupled to a common condenser that receives thermal energy from each cooling loop. A controller is coupled to the first and second cooling loop and adapts the operation of the first and second cooling loop in response to variances in operating conditions to provide cooling of the first and second MCM.

1. A computer system comprising:
 a first multiple chip module (MCM); 
 a second MCM positioned adjacent said first MCM; 
 a first evaporator thermally coupled to said first MCM, said first evaporator including a first expansion orifice; 
 a second evaporator thermally coupled to said second MCM, said second evaporator including a second expansion orifice; 
 a condenser thermally coupled to said first evaporator and said second evaporator; 
 a first cooling loop coupled between said condenser and said first evaporator, said first cooling loop having a first expansion valve; 
 a second cooling loop coupled between said condenser and said second evaporator, said second cooling loop having a second expansion valve; and, 
 a refrigeration controller operably coupled to said first expansion valve and said second expansion valve, said refrigeration controller having a processor responsive to executable computer instructions when executed on said processor for determining increase in demand of said first MCM and transmitting a first signal to said second expansion valve to increase a first operating temperature of said second evaporator in response to said determining of increased demand. 
 
     
     
       2. The computer system of  claim 1  further comprising:
 a first stepper motor operably coupled to said first expansion valve and electrically coupled to said refrigeration controller; and, 
 a second stepper motor operably coupled to said first expansion valve and electrically coupled to said refrigeration controller; 
 wherein said first signal is transmitted to said second stepper motor. 
 
     
     
       3. The computer system of  claim 2  wherein said refrigeration controller is responsive to computer executable instructions to transmit a second signal to said first stepper motor in response to an increase in temperature of said second MCM. 
     
     
       4. The computer system of  claim 2  further comprising:
 an air handler directly thermally coupled to said first MCM and said second MCM; 
 wherein said processor is responsive to computer executable instructions when executed on said processor to periodically and aperiodically operate said air handler and to calibrate said first expansion valve by transmitting a signal to said first stepper motor to close said first expansion valve. 
 
     
     
       5. The computer system of  claim 2  wherein said first cooling loop and said second cooling loop are fluidly coupled by a valve that is electrically coupled to said refrigeration controller, wherein said controller is responsive to computer executable instructions to transfer refrigerant from said first cooling loop to said second evaporator in response to a signal from a temperature sensor coupled to said second cooling loop. 
     
     
       6. A method of operating a computer cooling system having a first MCM and a second MCM, said method comprising:
 compressing a first refrigeration fluid in a first cooling loop to a high pressure gas; 
 condensing said first refrigerant to a high pressure liquid with a condenser; 
 expanding said first refrigeration fluid from a high pressure liquid to a first low pressure liquid with a first expansion valve; 
 expanding said first refrigerant fluid from said first low pressure liquid to a second low pressure liquid with a first orifice; 
 absorbing thermal energy from said first MCM into said second low pressure liquid to form a low pressure gas; 
 compressing a second refrigeration fluid in a second cooling loop to a high pressure gas; 
 condensing said second refrigerant to a high pressure liquid with said condenser; 
 expanding said second refrigeration fluid from a high pressure liquid to a third low pressure liquid with a second expansion valve; 
 expanding said second refrigerant from said third low pressure liquid to a fourth low pressure liquid with a second orifice; 
 absorbing thermal energy from said second MCM into said fourth low pressure liquid to form a low pressure gas; 
 changing the compression and expansion characteristics of said second refrigeration fluid to reduce the absorption of thermal energy from said second MCM in response to an increase in thermal energy produced by said first MCM. 
 
     
     
       7. The method of  claim 6  further comprising the step of controlling the temperature of said first refrigeration fluid second low pressure gas prior to compressing said first refrigeration fluid. 
     
     
       8. The method of  claim 6  further comprising the steps of:
 operating an air handler to directly remove thermal energy from said first MCM and said second MCM; 
 closing said first expansion valve after operating said air handler; and, 
 calibrating a controller to said first expansion valve. 
 
     
     
       9. The method of  claim 6  further comprising:
 transferring said first refrigerant second low pressure liquid to said second evaporator; 
 receiving said first refrigerant low fourth pressure gas from said second evaporator. 
 
     
     
       10. The method of  claim 9  further comprising:
 receiving a signal indicative of the temperature of said second evaporator; 
 absorbing thermal energy from said second evaporator with said first refrigerant fluid when said second evaporator temperature rises above a predefined threshold. 
 
     
     
       11. The method of  claim 6  further comprising:
 measuring an inlet temperature and an outlet temperature of said condenser; and, 
 changing the size of an orifice in said first expansion valve in response to said outlet temperature increasing above a predefined threshold. 
 
     
     
       12. The computer system of  claim 2  wherein said processor reduces the absorption of thermal energy in said second evaporator to maintain said first evaporator at a second operating temperature between 27° C.-31° C. 
     
     
       13. The computer system of  claim 12  wherein said second operating temperature is 29° C.